Adcom GDA-600 DAC tweak/mod

[MRswitch]

Hello all, i am from Ukraine. Bring to your attention DAC Adcom GDA-600 tweak on idea/offer of Ukranian master, who name is not disclosed yet by mee. To Tweek had a hand also, and I added some Components, which will be described below.
For the beginning about DAC's. This DAC is based on two chips PCM63-P-J.
Tweek / modernization was as follows:

• Dissected power supply, increases the capacity of the filters, replacement of diodes in the rectifier diodes for Schottky
• Removed the filter at PSU
• Was made a separate stabilizer for the analog supply and exhaust with electrolytes film and metallobumagoy filter
• Replaced the chip in the converter current \ AD817 voltage on the corresponding strapping
• Replaced the analog filter capacitors with film capacitors
• Replaced/removed several tens of details on the main board for better
• Transfer / separation of the components after the DAC chip, on a fee where includes: inverter current \ voltage, filter, analog amplifier stage on LME49710HA in a metal case
• Сhanged topology of grounding
• CS8412 digital receiver dir9001 replaced with less jitter

With regards my improvements:

1. The upper and lower parts of the case (under the board) was glued STP for noise / vibration and "electro" isolation. And upper part of case before my tweak have some special material, who names @chernomorit@
   

   He was placed to deal with noise and vibration on aircraft carriers in the compartments with radio equipment. Was different thicknesses. There was all the equipment on it. He was in the walls and under the floor.
   It consists of and what is metal - it should still partially screen . If his teeth crush it immediately felt like sinking your teeth , ie no energy is absorbed by the recoil like rubber (why teeth - greater degree of application of force in a limited space ) . It is chemically resistant , dimensionally unlike Vibration absorber on a bitumen basis . Excellent glued glue type BF and moments. Works best with large weights . Under heavy a greater effect than a light machine . ( before it was heavy)

2. In the PSU / filter was added two pairs of shunt capacitor
   MultiCap RTX 0.068uf / 100V & MultiCap PPMFX 0.01 / 600 V
3. Four of the six main capacitance capacitors from the the power supply capacitors was shunted JFX 1uf/250V (metallized polypropylene film capacitors.)

And also, the power cable has been replaced by an acoustic and silver-soldered solder TTAF

 

[MRswitch]

So, any question & propositions?

 

[MRswitch]

upd

Some upated!
Added capasitors ClarityCap ESA 1.5uf 250V
So and... look at foto, where shunt JFX 1uf/250V capasitors, on the other side of the board!

 

[mirach]

Hello Mr. switch, I hope that in your country the situation will go better in the future. However, congratulations for your work!

l also had fun to upset the devices in the past, now I've changed my philosophy. I think is better to spend the money for a new machine instead to do the tweak on it . But changing an old component, in respect of the initial project, with a new is a good things.
I also have an adcom gda 600. What do you think was the the greatest improvement? What has changed in the sound by replacing the CS8412 with the DIR9001?
thanks🙂

 

[MRswitch]

Thank you! We also hope.!
The fact that I got a DAC with a new receiver! I can not say about the changes, sorry. I Do not run for innovations, so long as PCM 63 suits me. CS8412 can be in some situations that would better, but it seems to me that in this case he does not play a major role, but only as one aspect of tweaks.